The present invention relates, in general, to programmable medical instruments for computing probabilities of medical outcomes or diagnoses.
A number of instruments have been developed that enable the physician to compute probabilities of life threatening cardiac conditions for patients. Some of these instruments are described in the following references, all of which are incorporated herein be reference.
A hand-held predictive instrument is described by Michael W. Pozen et al. in “A Predictive Instrument to Improve Coronary-Care- Unit Admission Practices in Acute Ischemic Heart Disease” The New England Journal of Medicine, Vol 310 pp. 1273-1278, May 17, 1984. With the handheld calculator-based instrument, a physician can compute a patient's probability of having acute cardiac ischemia based upon physician-entered values for a set of clinical variables. An automatic, computerized version of this instrument which utilizes output from a electrocardiograph and a waveform analyzer is described by H. P. Selker et al. in “A Time-Insensitive Predictive Instrument for Acute Myocardial Infarction Mortality”, Med. Care 1991; 29:1196-1211.
A predictive instrument for determining the probability of acute hospital mortality of a cardiac patient is described in U.S. Pat. No. 4,957,115 to Dr. Harry P. Selker, and incorporated herein by reference. The probability of acute hospital mortality is commonly understood to mean the probability of dying from a current acute condition, generally during the specific initial hospitalization for the problem. It is also know as the probability of imminent death for the patient. That is, it is a short term, as opposed to a long term, probability of mortality that does not necessarily have a precisely defined period of time associated with it.
A predictive instrument for evaluating whether to use thrombolytic therapy to treat a patient with a heart condition is described in U.S. Pat. No. 4,998,535 to Dr. Selker et al., and incorporated herein by reference. The predictive instrument computes a first probability of acute hospital mortality for the patient assuming that thrombolytic therapy is not administered and it computes a second probability of acute hospital mortality for the patient assuming that thrombolytic therapy is administered. The difference in the computed probabilities may assist the physician in deciding whether it would be advantageous to administer the thrombolytic therapy to the patient.
The above-mentioned predictive instruments use logistic regression equations to model the probability that the patient has a serious cardiac condition (e.g. the probability of acute cardiac ischemia or the probability of imminent death from a cardiac condition). Such predictive instruments have also been suggested for other medical conditions or medical outcomes. See for example, U.S. Pat. No. 5,724,983 to Dr. Selker et al. also incorporated herein by reference.